Valve

ABSTRACT

A sliding spool valve ( 1 ) is provided for controlling flow of fluid especially between an inlet ( 2 ) at a relatively high pressure and an outlet ( 6 ) at a relatively low pressure. Wherein the spool valve is reciprocally displaced between open and closed positions by hydraulic action of the transmitted fluid.

This invention relates to a valve for use in controlling the flow of atransmitted fluid and in particular to a valve that is actuated betweenopen and closed positions using the pressure of transmission of thefluid that the valve controls.

Actuated valves are well known, but their actuators are usually drivenby an external independent energy source which is either electric, inthe case of solenoid actuators, or driven by pressure from a separatehydraulic or pneumatic system or circuit. If there is a failure of theenergy source, or a disruption of the separate pressurised circuit,actuation of the valve fails. In addition, such actuators are relativelyexpensive and require a number of different materials for theirmanufacture.

An object of the present invention is to provide a fluid flow controldevice with an actuator that can open or close a control valve withoutthe aid of an independent energy source for motive power. This providesthe benefits of reliability of operation, low cost, ease of installationand is also proof against vandalism or consumer tampering.

Accordingly, the present invention provides a sliding spool valve forcontrolling flow of a fluid transmitted between an inlet at a relativelyhigh pressure and an outlet at a relatively low pressure, the spoolvalve comprising first and second opposed ends and first and secondhydraulic actuators, each hydraulic actuator acting on one of theopposed ends of the sliding spool valve, wherein the spool valve isreciprocably displaced between open and closed positions by hydraulicaction of the transmitted fluid selectively acting on the first andsecond hydraulic actuators, characterised in that each hydraulicactuator comprises a piston reciprocably slidable in a bore topressurise a working fluid which acts on one of the opposed ends of thespool valve, means being provided for retaining the pistons of thehydraulic actuators in positions equating to the open and closedpositions of the spool valve, wherein the means for retaining thepistons is operated by any of an electronic, electromagnetic ormechanical trigger.

An advantage of the spool valve of the present invention is that itderives its motive force from a mechanical advantage gained over thedifference in pressure upstream and downstream of the device through asystem of force intensifiers. The fluid used to drive the actuator isdischarged back into the transmission conduit, downstream of the valve.A further advantage is that a compact apparatus is provided combiningboth valve and actuator elements.

An embodiment of the present invention will now be described withreference to the accompanying drawings, in which:

FIG. 1 is a schematic representation of a valve according to the presentinvention in a closed position;

FIG. 2 is a schematic representation of the valve of FIG. 1 in anintermediate position; and

FIG. 3 is a schematic representation of the valve of FIG. 1 in an openposition.

The valve of the present invention, illustrated in FIG. 1, consists of asliding spool valve 1, with first and second opposed ends, one inletport 2, three outlet ports 3, 5, 6 and a bypass duct 4.

The upstream outlet port 3 discharges into a cylinder with threechambers, the outer chamber 7 is fitted with a piston 8 which acts as aforce intensifier whose smaller end moves within a middle chamber 9which is filled with an inert, incompressible, non-toxic fluid. Theinner chamber 10 is wider and forms a force intensifier at one end ofthe spool valve 1. The piston 8, outer chamber 7, middle chamber 9 andinner chamber 10 together comprise a first hydraulic actuator. Atrigger/lock mechanism 26 is provided in outer chamber 7 to controlmovement of the piston 8.

The downstream outlet port 6 also discharges into a cylinder ofidentical dimensions and function. The outer chamber 11 that isconnected to the downstream outlet port 6 is fitted with a piston 12which acts as a force intensifier whose smaller end moves within amiddle chamber 13 that is filled with an inert, incompressible,non-toxic fluid. The inner chamber 14 is wider and forms a forceintensifier at the opposite end of the spool valve 1. The piston 12,outer chamber 11, middle chamber 13 and inner chamber 14 togethercomprise a second hydraulic actuator. A trigger/lock mechanism 28 isprovided in outer chamber 11 to control movement of the piston 12.

The outer chambers 7, 11 of the hydraulic actuators are interconnectedby a pressure balancing duct 15 with the void being filled with an inertnon toxic gas such as air.

The inlet port 2 is connected by a duct 16 to a pressure receiver 17,which is partitioned with a flexible and resilient diaphragm 18. Thedownstream end of the receiver is connected by a duct 19 to the outerchamber of the cylinder 11 and connected to the downstream outlet port 6by a duct 27.

The intermediate outlet port 5 discharges to a pressure receiver 20fitted with a resilient and flexible diaphragm 21. The confined spacebehind the diaphragm 22 is filled with an inert non-toxic gas such asair whose pressure is set at a predetermined level dependent on thecharacteristics of the mechanism.

The landings 24 on the spool valve 1 are arranged in such a way that itacts as a four-way three-position valve. In the closed position, theinlet port 2 is connected to the upstream outlet port 3 while theintermediate outlet port 5 is connected to the downstream outlet port 6.There is no flow of fluid through the valve. In the intermediateposition all the outlet ducts 3, 5, 6 are open to each other through thebypass duct 4. There is no flow through the valve during this stage. Inthe open position, the inlet port 2 is connected to the downstreamoutlet port 6 while the intermediate outlet port 5 is open to theupstream outlet port 3. Fluid can flow through the valve.

The closed position is illustrated in FIG. 1. In this position, the face23 of the piston with the larger surface area in the outer chamber 7 isconnected to the upstream outlet port 3 is subject to the ambientpressure at the inlet port 2. The force exerted by this pressure isconveyed from the piston small end 25 through the fluid in the middlechamber 9 and inner chamber 10 to the first opposed end of the spoolvalve 1. The force is magnified due to the dimensions of the chambers.Upon release of the trigger/lock mechanism 26 this force creates animpulse driving the spool valve 1 to slide from the closed positionthrough an intermediate position of the landings to an open position. Inthis way, the force produced by the pressure of the transmitted fluid atinlet port 2 acts to displace the spool valve 1 towards the openposition. The changes of the position of the landings with respect tothe ports causes flows and pressure conditions to change within thedevice.

The intermediate position is illustrated in FIG. 2. In this position theoutlet ports 3, 4, 5 and 6 are all open to each other. As the spoolvalve slides from the closed position through its intermediate positionto the open position, it transmits the impulsive force into the fluid ofthe inner chamber 14 and middle chamber 13 of the second hydraulicactuator connected to the downstream outlet port 6. This drives itspiston 12 to discharge the fluid in the outer chamber 11 through thewaste duct 27. This is possible where there is a difference in pressureupstream and downstream of the valve. While this takes place, pressureand fluid is compensated in the outer chamber 7 connected to the inletport 2 by an influx of pressurised fluid from the compensating reservoir20 moving through the intermediate outlet port 5, by-pass duct 4 andoutlet port 3. When the piston 12 reaches the position where the valveis open, it is held there by a spring-loaded trigger/lock mechanism 28.

The open position is illustrated in FIG. 3. In this position, the face29 of the piston with the larger surface area in the outer chamber 11 ofthe second hydraulic actuator connected to the downstream outlet pert 6is subject to the dynamic pressure of the fluid that is passing throughthe valve. The force exerted by this pressure is conveyed from thesmaller end of the piston 30 through the fluid in the middle camber 13and inner chamber 14 to act on the second opposed end of the spool valve1. The force is magnified due to the dimensions of the chambers. Uponrelease of the trigger/lock mechanism 28 this force creates an impulsedriving the spool valve to slide from the open position through anintermediate position of the landings to the closed position. When thepiston 8 reaches the position where the valve is shut, it is held thereby the spring-loaded trigger/lock mechanism 26.

As the spool valve 1 slides from the open position through itsintermediate position to the closed position, it transmits the impulsiveforce into the fluid of the inner chamber 10 and middle chamber 9 of thefirst hydraulic actuator connected to the inlet port 2. This drives itspiston 8 to discharge the fluid in the outer chamber 7 through theupstream outlet port 3 initially into the pressure receiver 20 whichaccommodates the volume by distending the diaphragm 21 into the lowpressure void 22. As the spool valve 1 reaches the closed position thepressure in the vessel is equalised to the downstream pressure when theintermediate outlet port 5 is opened to the downstream outlet port 6.

As the valve closes, the inlet port 2 is subject to the effects of waterhammer, which will tend to momentarily increase pressure at the inlet.The pressure increase is transmitted through a duct 16, via thediaphragm 18 in the pressure vessel 17 to the outer chamber 11 of thesecond hydraulic actuator connected to the downstream outlet port 6 andacts to assist the piston 12 to drive the toggle 1 to the closedposition. The diaphragm 18 allows the transmission of water hammerpressure while containing the flow of fluid through the system.

The valve can be used to control the flow of any fluid where there is adifferential pressure upstream and downstream of the valve. It is suitedto control flows of water, gas, or any other fluid that is conveyedunder pressure through a large-scale distribution network. It can befabricated from any material capable of sustaining the working pressuresthe valve will be subjected to such as metal or plastic. Advantageously,the valve may be manufactured from less expensive materials such asplastics and may be manufactured from one, or only a small number of,different materials.

The valve is also simply to install since connections are only requiredfor the transmitted fluid inlet and outlet.

The spool valve 1 may be operated between the open and closed positionsremotely by using an electronic, electromagnetic micro-switch ormechanical trigger to operate the trigger/lock mechanisms 26, 28. Forexample, a radio signal may be used to operate the trigger/lockmechanisms 26, 28 from a remote control station. Alternatively, a signalto operate the mechanisms 26, 28 may be sent electronically overtelephone lines, the Internet or by satellite transmission.

Advantageously, the valve requires only minimal additional power inorder to operate. Only the power required to operate the trigger/lockmechanisms 26, 28 need be supplied by an additional power source sincethe transmitted fluid provides the energy necessary to open and closethe valve mechanism itself. This makes the valve particularly suitablefor use in remote or hazardous locations where it is uneconomic ordifficult to provide external power supplies. It also renders the valveless prone to tampering by the end user since the valve does not dependon a major external power source, such as an electric power outlet,which may be tampered with by the user. For example, the trigger/lockmechanisms may be powered from a self-contained battery which isinaccessible to the user.

The valve can also be made to generate electricity for storage in arapid discharging capacitor and used to power the trigger/lockmechanisms 26, 28. This can be achieved by providing a magnet in thecasing of the outer chambers 7, 11 and a conductive coil in the pistons8, 12. When the pistons move to and fro due to the pressure of thetransmitted fluid and the working of the spool valve an electricalcurrent will be generated. This can be stored in the capacitor to powerthe trigger/locking mechanisms making the valve completely selfcontained and self sustaining.

1. A sliding spool valve for controlling flow of a fluid transmittedbetween an inlet at a relatively high pressure and an outlet at arelatively low pressure, the spool valve comprising first and secondopposed ends and first and second hydraulic actuators, each hydraulicactuator acting on one of the opposed ends of the sliding spool valve,wherein the spool valve is reciprocally displaced between open andclosed positions by hydraulic action of the transmitted fluidselectively acting on the first and second hydraulic actuators,characterized in that each hydraulic actuator comprises a pistonreciprocally slidable in a bore to pressurize a working fluid which actson one of the opposed ends of the spool valve, a lock mechanism beingprovided for retaining the pistons of the hydraulic actuators inpositions equating to the open and closed positions of the spool valve,wherein the lock mechanism for retaining the pistons is operated by anyof an electronic, electro-magnetic or mechanical trigger.
 2. A slidingspool valve as claimed in claim 1, wherein each hydraulic actuator has afirst end with a larger surface area and a second end with a smallersurface area, the pressure of the transmitted fluid selectively actingon the first end of each hydraulic actuator and the second end of eachhydraulic actuator acting on one of the oppposed ends of the spoolvalve.
 3. A sliding spool valve as claimed in claim 1, wherein thetrigger is operated remotely.
 4. A sliding spool valve as claimed inclaim 1, wherein the trigger is powered by an internal power source. 5.A sliding spool valve as claimed in claim 1, wherein the trigger ispowered by an electrical capacitor.
 6. A sliding spool valve as claimedin claim 5, wherein the capacitor is charged by movement of a coil on atleast one of the pistons with respect to a magnet.
 7. A sliding spoolvalve as claimed in claim 1, wherein the spool valve is an open-centrespool valve.
 8. A sliding spool valve as claimed in claim 7, wherein thespool valve is a three-position, four-way valve.
 9. A sliding spoolvalve as claimed in claim 8, further comprising an inlet port connectedto the inlet, a first outlet port communicating with the first end ofthe first hydraulic actuator, a second outlet port communicating withthe first end of the second hydraulic actuator and the outlet, whereinin the closed position of the spool valve the inlet port and the firstoutlet port are in pressure and fluid communication and the inlet portand the second outlet port are not in fluid communication such thatfluid and pressure is not transmitted between the inlet and outlet, andin the open position the inlet port and the second outlet port are influid communication such that fluid is transmitted between the inlet andoutlet, and wherein in the closed position the spool valve is biasedtowards the open position by the first hydraulic actuator, and in theopen position the spool valve is biased towards the closed position bythe second hydraulic actuator.
 10. A sliding spool valve as claimed inclaim 9, further comprising a third outlet port communicating with apressure receiver.
 11. A sliding spool valve as claimed in claim 9,further comprising a by-pass duct, wherein in an intermediate positionof the spool valve between the open and closed positions, the firstoutlet port, second outlet port and third outlet port are in mutualfluid communication.
 12. A sliding spool valve as claimed in claim 9,wherein a pressure vessel is provided in fluid communication with theinlet port to transmit a water hammer pressure increase to the secondhydraulic actuator as the spool valve closes.
 13. A sliding spool valveas claimed in claim 1, wherein the transmitted fluid is any of water,oil, or natural gas.
 14. A sliding spool valve as claimed in claim 1,wherein the sliding spool valve is made substantially from plastic. 15.A sliding spool valve as claimed in claim 1, wherein the sliding spoolvalve is made substantially from metal.